Both low density lipoproteins and very low density lipoproteins have been implicated as positive risk factors in the genesis of atherosclerosis, whereas high density lipoprotein concentration is an independent negative risk factor. Both diabetes and obesity are associated with changes in plasma lipoproteins and these changes may be related to the increased prevalence of cardiovascular disease. We are studying lipoprotein composition in obese and diabetic Pima Indians. Cholesterol and triglycerides are being measured in VLDL, LDL, and HDL, as well as in HDL subclasses isolated by ultracentrifugation. These parameters are being compared in grops of normal and diabetic Indians with and without coronary artery disease, and the influence of therapy is being assessed. Apoprotein composition of specific lipoproteins will be measured. From this study we will attempt to determine if diabetes and obesity are associated with changes in serum lipoproteins and to delineate the relation between lipoprotein levels and the pathogenesis of ischemic heart disease.